NFS: Remove fscache specific trace points and NFS_INO_FSCACHE bit

The NFS specific trace points are no longer needed as tracing is well
covered by netfs and fscache.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Daire Byrne <daire@dneg.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>